1 . Technical Field
This disclosure relates o an image forming apparatus.
2 . Description of the Related Art
Image forming apparatuses are used as printers, facsimile machines, copiers, plotters, or multi-functional devices having, e.g., two or more of the foregoing capabilities. For example, there is known an image forming apparatus such as a label printer which prints on a roll print medium (hereinafter also referred to as “label sheet”), such as a tape and a label sheet, and which cuts the medium into desired length after printing to form a print medium piece (hereinafter also referred to as “label piece”).
A band-like marking (hereinafter, “I-shaped mark” or also referred to as black mark) to provide an indication of size is added on a surface of the label sheet opposite to a recording surface of the label sheet. The image forming apparatus includes a detector to detect the I-shaped mark to detect a position of the label sheet in a conveyance direction of the label sheet.
For example, there is conventionally known an apparatus including a label roll holder which rotatably holds a label roll, a thermal head which prints predetermined items on a printing surface of a label sheet, a sheet conveyance path through which a label sheet pulled out from the label roll is conveyed, a pair of guide plates which guide the label sheet conveyed through the sheet conveyance path, a sheet sensor which detects presence or absence of label sheets and/or detects a position of a label sheet, and a projection formed in the vicinity of the sheet sensor in one of the pair of guide plates that is opposed to a back surface of the printing surface of the label sheet (JP 2000-052612 A).
For example, when a belt member (belt member) is used for conveying a print medium, a detector (reader) is disposed inside the belt member to read a back surface (surface which comes into contact with the belt member) of the print medium like the roll label sheet. To dispose the detector, a transparent body is used as a belt member, thus increasing costs.
It is also conceivable to detect a marking on a back surface of a label in front of the belt member, and to record and cut the label based on information of the marking. However, such a configuration may result in a reduced precision of a recording position and a cut position. Such a configuration may also hamper precise position detection of a label region which is set on the belt member at the time of initial setting, thus resulting in wasteful abandonment.